1. Technical Field
The present invention relates to a tunable interference filter, an optical module including the tunable interference filter, and an electronic apparatus including the optical module.
2. Related Art
A tunable interference filter in which reflection films are respectively oppositely provided across a predetermined gap on surfaces opposed to each other of a pair of substrates is known (for example, see JP-A-2002-277758).
In the tunable interference filter disclosed in JP-A-2002-277758, the reflection layers are respectively provided on the opposed surfaces of two optical substrates, and capacitance electrodes are provided at the outer sides in the radial direction of the reflection layers on the opposed surfaces of the optical substrates. In the tunable interference filter, the capacitance electrodes opposed to each other act as an electrostatic actuator, and a voltage is applied between the capacitance electrodes to vary the gap between the reflection layers by an electrostatic attractive force.
In the tunable interference filter, an electric charge may accumulate on the reflection layers, and, if the reflection layers opposed to each other are respectively charged, an electrostatic force is generated. Accordingly, even in the case where a predetermined set voltage is applied to the electrostatic actuator for setting the gap between the reflection layers to a set value, the gap may not be set to the desired set value due to the electrostatic force on the charged reflection layers. In this case, there is a problem that it is difficult to extract light having a desired wavelength from the tunable interference filter.